Recent prospective clinical trials have shown that cardioverter-defibrillators, such as implantable cardioverter-defibrillators (ICDs), reduce sudden arrhythmic death and favorably impact overall mortality in patients at risk for spontaneous ventricular tachyarrhythmia. Cardioverter-defibrillator systems are designed to provide therapy when rapid ventricular activation rates are sensed. However, rapid ventricular rhythms can occur in the presence of a supraventricular tachycardia (SVT). When therapy is applied in response to SVT (in absence of a ventricular tachycardia, VT, or ventricular fibrillation, VF), the therapy is classified as clinically "inappropriate", even though the cardioverter-defibrillator responded appropriately to an elevated ventricular rate.
Cardioverter-defibrillators may deliver inappropriate ventricular therapy to patients afflicted with non-malignant SVTs. These inappropriate therapies may be delivered due to the device's inability to reliably discriminate SVT from malignant VT.
For the reasons stated above, and for other reasons stated below which will become apparent to those skilled in the art upon reading and understanding the present specification, there is a need in the art for a system and a method of reliably and accurately discriminating between the occurrence of a SVT and a VT event during a detected tachyarrhythmia event which can reduce the frequency of inappropriate therapies delivered to cardioverter-defibrillator patients. Such a system may also be suitable for use with patients having implantable cardioverter-defibrillators.